Inhibiting the growth of bacteria in absorbent articles by adding other bacteria

ABSTRACT

The invention relates to absorbent articles, such as diapers and like articles and is concerned with methods for preventing undesirable odors and/or preventing the growth of undesirable microorganisms when the articles are in use, and also provides an absorbent article which can be worn for long periods of time without generating undesirable odors, incurring the risk of infection or having a negative effect on skin. Another object is to amplify the presence in the wearer&#39;s urogenital zone of microbiological flora that will assist in preventing the occurrence of urinal tract infections. These objects have been achieved by adding to the absorbent articles microorganisms which exhibit antagonistic properties against present undesirable strains of microorganisms, so as to restrain the growth of these or establishing of new undesirable species.

TECHNICAL FIELD

The present invention relates to absorbent articles such as diapers,incontinence guards, sanitary napkins and like articles, and isconcerned with methods of preventing the generation of undesirable odorsand/or the growth of undesirable microorganisms as the article is worn.

PROBLEMS

Many designs of absorbent articles of this kind are known to the art.Conventionally, the absorbent body of such articles is produced bydry-defibering cellulose pulp contained for instance in rolls, bales orsheets, and transforming the fluffed pulp to a pulp mat, sometimes whileadmixing so-called superabsorbents, which may be polymers capable ofabsorbing several times their own weight in water or body fluid.

The absorbent body may also include other components, for instancecomponents that will improve the ability of the absorbent body totake-up and disperse liquid, and that will increase its coherency andits ability to resist deformation in use.

Articles of this kind are liable to generate undesirable odors when inuse, caused among other things by microbial metabolism, biological orchemical decomposition of components in body fluids, such as urine ormenstruation fluid, for instance.

Another problematic area associated with the use of absorbent articlesis the risk of infection caused by pathogenic microorganisms.

Another problem is found in the working environmental risks that canarise when handling soiled diapers that contain a large quantity ofmicroorganisms. The growth of microorganisms that can take place in asoiled, used diaper during its storage after use can contribute toelevated odor problems and can also increase the risk of spreadingundesirable microorganisms.

Another problem is the different forms of skin irritation and skininfections that can be caused directly or indirectly by microorganisms.

Microorganisms or their products that are known to contribute to theoccurrence of undesirable odors, to cause infections in the urinal tractor to be associated with the occurrence of skin problems are, forinstance such microorganisms as Proteus, Pseudomonas, Escherichia,Klebsiella, Enterococcus, Staphylococcus, Streptococcus and Candida.

DESCRIPTION OF THE KNOWN PRIOR ART

Different methods of alleviating the aforedescribed problems have beenproposed. The International Patent Applications WO 91/11977 and WO91/12031 describe methods of adsorbing undesirable odors in zeoliteincluded in the absorbent article. U.S. Pat. No. 4,385,632 describes theaddition of copper salt to a diaper with the intention of preventing thedecomposition of urea to ammonia and therewith prevent the occurrence ofunpleasant smells.

U.S. Pat. No. 3,794,034 describes the significance of pH in an absorbentarticle, and the significance of impregnating the article with abuffering substance by means of which the pH of the article can bemaintained at between 3.5 and 6.0, which is advantageous from both theaspect of inhibiting the growth of undesirable bacteria, and therewiththe generation of undesirable odors, and in avoiding a negative effecton the skin. European Patents EP 202127 and EP 311344 describe theadjustment of pH in absorbent articles that include superabsorbentmaterial. Since buffering substances can have a negative effect on manysuperabsorbent materials, it is necessary to take separate measures toavoid undesirable effects. In the case of European Patent EP 202127, thesuperabsorbent material and buffering substances are placed in mutuallyseparated zones in the absorbent article. In the case of European PatentEP 311344, the buffering and the superabsorbent properties have beencombined in one and the same material, and a separatebacteria-inhibiting substance has also been added.

The drawback with these described methods is that when only anodor-absorbing agent is added, the bacteria are still able to grow, andthe bacteria inhibiting agents, which are often selective, can createrisks, for instance, in the form of allergenic properties or negativeecological consequences when handling waste. Furthermore, the use ofthis type of agent involves the risk that resistant strains will occur.

It is known within the medicine and foodstuff technologies to usebioconservation with the aid of bacterial antagonism as a conservingmethod, and to inoculate special bacteria strains to favourize bacteriapopulations that are beneficial to the stomach and intestines, forhealth-promoting purposes. Examples in this respect are conventionalyoghurt and soured milk, and also novel bioactive foodstuffs. Thismethodology also includes the use of bacteria such as so-calledprobiotic bacteria as a substitute for antibiotic bacteria.

Canadian Patent CA 1,298,556 teaches the medical use of selected strainsof lactobacteria, wherein, among other things, whole cells or cellfragments of Lactobacillus are used to treat or preclude the occurrenceof urinal tract infections. International Patent Application WO 93/09793describes the use of lactobacteria and skimmed milk preparations forprecluding or preventing urogenital infections. International PatentApplication WO 92/13577 describes a tampon or sanitary napkin that hasbeen impregnated with a culture of lactic-acid producing bacteria,preferably of the genus Pediococcus, isolated from healthy individuals.The tampon or sanitary napkin is intended for the prophylactic treatmentof urogenital infections.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an absorbent articleof the kind mentioned in the introduction which will allow the articleto be worn, even for a long period, without permitting microorganisms togrow or to become active to an extent such as to promote undesirableodors, to incur the risk of infection or to have a negative effect onthe skin. Another object of the invention is to enable antagonisticmicroorganisms to be transferred to the wearer so as to amplify in thewearer's urogenital zone the occurrence of such microbiological flora asthose that will assist in preventing the occurrence of urinary tractinfection. These objects have been achieved in accordance with theinvention by adding to the absorbent article microorganisms whichexhibit antagonistic properties against present undesirable strains orarising undesirable strains of microorganisms present in the absorbentarticle or in the urogenital zone of the wearer during regular use ofthe absorbent article, wherein said microorganisms are added in anamount and have an activity such as to restrain the growth ofundesirable species or establishing of new undesirable species ofmicroorganisms.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates in terms of percentage the proportion of differentbacteria strains that exhibit inhibited growth in the presence ofantagonistic strains.

DETAILED DESCRIPTION OF THE INVENTION

The object of the present invention is to provide an absorbent articleof the kind mentioned in the introduction which will enable the articleto be worn for a relatively long period of time without microorganismsbeing allowed to grow to an extent in which undesirable odors aregenerated, in which the risk of infection is created, or to an extentwhich will have a negative effect on skin. A further object of theinvention is to enable antagonistic microorganisms to be transferred tothe wearer so as to amplify in the wearer's urogenital zone the presenceof microbiological flora that will assist in preventing the occurrenceof urinal tract infections.

Bacteria that cause unpleasant smells may belong to, for example, thefamily Enterobacteriaceae, e.g. Proteus mirábilis, Proteus vulgaris,Escherichia coli and Klebsiella.

Bacteria that cause urinal tract infections may belong to, for example,the families Enterobacteriaceae and Micrococcaceae or the genusStreptococcus. Examples of species and genera are Escherichia coli,Proteus mirábilis, Enterococcus, Klebsiella, Staphylococcus andStreptococcus.

Microorganisms associated with skin infections are Ascomycetes,Pseudomonadaceae and Micrococcaceae and the genus Streptococcus, e.g.Candida albicans, Pseudomonas, Staphylococcus and Streptococcus.

The invention is based on microbiological antagonism. This implies thatone microorganism or combinations of microorganisms inhibits/inhibitother microorganisms by competing for substrate, changing pH, formingenzymes, toxins, carbon dioxide, peroxides or antibiotics, so-calledbacteriocines.

Antagonistic microorganisms may be naturally occurring microorganismswhich are non-toxic and do not have any negative biological effect onhumans, in the form of infections or skin changes.

Antagonistic microorganisms may also be produced biotechnically.

The addition to an absorbent article of microorganisms which exhibitantagonistic properties against such undesirable strains ofmicroorganisms that are present when the absorbent article is wornregularly, is able to restrain the growth of these undesirable strainsof microorganisms or establishing of new undesirable strains. Even somekilling of microorganisms of undesirable species may occur. It isnecessary for the microorganisms to have an activity and to be added inamounts which will achieve the desired effect. Normally, this effect isachieved when the number of antagonistic microorganisms per absorbentarticle exceeds 10⁶ cfu, preferably 10⁸ cfu, more preferably 10⁹ cfu. Byregular use is meant in this case daily use of an article with thearticle replaced several times during a calendar day, as is the casewith products intended for use with children or incontinent adults. Theterm regular use may also include the use relevant to sanitary napkinsor tampons during a menstruation period.

One advantage afforded by the use of antagonistic microorganisms is thatthere is avoided an undesired selection pressure on the microenvironment, such as favouring potential disease-promotingmicroorganisms and therewith the risk of developing pathogenic strainsthat are resistant to antibiotics and chemopharmaceutical preparations.Since the antimicrobial system is based on a natural, biologicalprocess, there is less risk of environmental ecological and toxicdisturbances.

An antagonistic strain shall exhibit a growth-inhibiting effect onseveral of the aforesaid undesired microorganisms, with conventionalinterference techniques.

A desired antagonistic microorganism shall also be capable of survivingin storage and to retain its growth ability or its ability to retain itsactivity in the absorbent article when worn.

The microorganisms that exhibit antagonistic properties may be bacteriaor other microorganisms, for instance fungi. When the antagonisticmicroorganisms are bacteria, these bacteria are preferably selected fromthe family Lactobacillaceae and particularly from the generaLactobacillus or Lactococcus and preferably from the speciesLactobacillus acidophilus, Lactobacillus curvatus, Lactobacillusplantarum or Lactococcus lactis.

An absorbent article produced in accordance with the invention mayinclude a permeable outer sheet which is intended to lie proximal to thewearer in use, a preferably liquid-impermeable backing sheet which isintended to lie distal from the wearer in use, and an absorbentstructure placed between the outer sheet and the backing sheet. In somecases, an additional sheet in the form of, e.g., wadding or likematerial, may be placed between the outer sheet and the absorbentstructure. The microorganisms exhibiting antagonistic properties may beplaced in different parts of the absorbent article, for instance in theouter sheet, in the absorbent structure of the absorbent article,between two of the layers in the absorbent article, in a loose insertproduct in the absorbent article, or in some other way.

The following Examples illustrate the effect of antagonistic bacteriastrains in more detail.

EXAMPLE 1

Synthetic urine to which a microorganism growth medium had been addedwas used as a test liquid. The synthetic urine contained monoions,divalent ions, cations and anions and urea and was prepared inaccordance with information contained in Geigy, Scientific Tables, Vol.1, 8th ed., 1981, p. 53. The microorganism growth medium was based oninformation concerning Hook and FSA media for enterobacteria.

EXAMPLE 2

Tests were carried out in accordance with the “agar overlay” method withthe intention of studying bacterial antagonism. The method is based onthe growth-inhibiting substance produced by the lactobacteria diffusingthrough an agar layer and inhibiting the growth of the test organisms.

Lactic acid bacteria, five strains of Lactobacillus and three strains ofLactococcus, were cultivated to an overnight culture in a suitablebroth. Lactococcus were cultivated in M17 and Lactobacillus werecultivated in MRS. Agar (2%) of M17 and MRS (25 ml) respectively weremixed with 1.0 ml of respective bacteria and moulded in a petri dish.The Agar plates were incubated overnight at 37° C. The plates thatcontained MRS were incubated in a CO₂ atmosphere. Reference plates wereprepared in a corresponding manner, but without lactic acid bacteria. Afurther layer containing 25 ml agar was moulded on top of the layerpresent in the petri dishes and allowed to solidify.

The test organisms, in the form of Gram-negative bacteria ofrespectively Escherichia coli, Klebsiella spp and Proteus spp, and 100,91 and 50 strains respectively, were cultivated in a broth and adilution corresponding to 10⁷ cfu/ml was prepared in a Bertani tray. Thetest bacteria were then stamped on the new agar layer with the aid of aso-called steers steel pin replicator. The plates were incubated at 37°C. for twenty-four hours. At the end of the incubation period, theplates were scanned and compared with the reference plates. “Growth”,“inhibition” and “zero growth” were registered for respective testorganisms when scanning the plates. All agar layers were measured withregard to pH, and plates having a pH beneath 5.0 were retested withpH-adjusted agar.

The results are listed in Tables 1-6 and shown in FIG. 1. The totalnumber of test organisms that had been inhibited or given zero growthwere calculated in percentage units. The results show that the growth ofrespective test organisms Escherichia coli, Klebsiella and Proteus wasgreatly inhibited by the presence of genera Lactobacillus while someinhibition was obtained in the presence of genera Lactobacillus.

TABLE 1 Test organism Escherichia coli Lactococcus Growth InhibitionZero growth Inhibition or No. number number number zero growth L 3 85 141 15 L 4 91 9 1 10 L 5 65 7 28 35 L 9 4 0 96 96 L 26 0 0 100 100

TABLE 2 Test organism Escherichia coli Lactobacillus Growth InhibitionZero growth Inhibition or No. number number number zero growth LB 13 0 0100 100 LB 14 0 2 98 100 LB 16 0 2 98 100

TABLE 3 Test organism Klebsiella spp Lactococcus Growth Inhibition Zerogrowth Inhibition or No. number number number zero growth L 3 68 16 7 25L 4 71 23 6 32 L 5 64 10 17 29 L 9 51 10 30 44 L 26 34 36 21 63

TABLE 4 Test Organism Klebsiella spp Lactobacillus Growth InhibitionZero growth Inhibition or No. number number number zero growth LB 13 0 091 100 LB 14 62 22 7 32 LB 16 0 0 91 100

TABLE 5 Test organism Proteus spp Lactococcus Growth Inhibition Zerogrowth Inhibition or No. number number number zero growth L 3 47 2 1 6 L4 49 1 0 2 L 5 39 7 4 22 L 9 45 4 1 10 L 26 36 8 6 28

TABLE 6 Test organism Proteus spp Lactobacillus Growth Inhibition Zerogrowth Inhibition or No. number number number zero growth LB 13 0 0 50100 LB 14 10 19 21 80 LB 16 0 7 41 96

EXAMPLE 3

Five test products were produced, each consisting of a pulp body thatcomprised a fibre mixture of 50% chemithermomechanical cellulose pulpand 50% chemical cellulose pulp with an addition of about 5%superabsorbent material. The pulp body was sandwiched between apermeable nonwoven material having a surface weight of 23 g/m² and animpervious backing sheet comprised of 33 μm polyethylene film. A layerof polyester wadding having a surface weight of 65 g/m² was placedbetween the nonwoven sheet and the pulp body. A mixture of freeze-driedlactobacteria of genus Lactobacillus was placed between the wadding andthe pulp body in an amount corresponding to 10⁸ bacteria per testproduct. 50 ml of synthetic urine according to Example 1 were thenapplied to the pulp body. The presence of lactobacteria in the groinsand at the mouth of the urethra of five test subjects was measured,whereafter the subjects wore respective test products for two hours inthe manner of a diaper or sanitary napkin. The presence of lactobacteriain the groins and at the mouth of the urethras of the test subjects wasthen again measured. The results are set forth in Table 7. It will beseen from the Table that the freeze-dried lactobacteria were activatedwhen the test products were worn by the test subjects and that theselactobacteria were also transferred to the test subjects.

TABLE 7 Start value Start value After 2 hrs. After 2 hrs. urethra groinurethra groin number number number number Test lacto- lacto- lacto-lacto- person bacteria bacteria bacteria bacteria No. 1 No growth Nogrowth 3.6 × 10³ 1.5 × 10⁴ No. 2 No growth No growth 2.8 × 10³ 2.7 × 10²No. 3 No growth No growth 1.4 × 10³ 8.4 × 10² No. 4 No growth No growth3.8 × 10⁶ 4.0 × 10³ No. 5 No growth No growth 4.5 × 10³ 8.6 × 10²

It will be understood that the invention is not restricted to theillustrated and described exemplifying embodiment thereof and that otherembodiments are conceivable within the scope of the following Claims.

What is claimed is:
 1. In an absorbent diaper including addedmicroorganisms, the improvement wherein the added microorganisms areselected from genera Lactobacillus or Lactococcus, and exhibit, when theabsorbent diaper is worn regularly by a wearer for a short or longerperiod, antagonistic properties against undesirable strains ofmicroorganisms from the families Enterobacteriaceae, Micrococcaseae,Psuedomonadaceae and Ascomycetes and the genus Streptococcus, andpresent or arising in the absorbent diaper or in the urogenital zone ofthe wearer of said absorbent diaper; and wherein the addedmicroorganisms are added in such quantities and have such activity as torestrain the growth of undesirable species of microorganisms to such anextent as to prevent the generation of undesirable odors in theabsorbent diaper.
 2. The absorbent diaper according to claim 1, whereinthe added microorganisms are antagonistic bacteria selected from speciesLactobacillus acidophilus, Lactobacillus curvatus, Lactobacillusplantarum or Lactococcus lactis.
 3. The absorbent diaper according toclaim 1, wherein the number of added microorganisms per absorbentarticle exceeds 10⁶ cfu.
 4. The absorbent diaper according to claim 3,wherein the number of added microorganisms per absorbent article exceeds10⁸ cfu.
 5. The absorbent diaper according to claim 4, wherein thenumber of added microorganisms per absorbent article exceeds 10⁹ cfu. 6.The absorbent diaper according to claim 1, wherein the addedmicroorganisms are such that they exhibit antagonistic propertiesagainst one or several undesirable strains selected from species Proteusmirabilis, Proteus vulgaris, Escherichia coli, Candida albicans and thegenera Klebsiella, Enterococcus, Staphylococcus, Streptococcus andPseudomonas.
 7. In an absorbent diaper comprising a permeable outersheet which in use is intended to lie proximal to a wearer, aliquid-impermeable backing sheet which in use is intended to lie distalfrom the wearer, and an absorbent structure positioned between the outersheet and the backing sheet, the absorbent diaper including addedmicroorganisms, the improvement wherein the added microorganisms areselected from genera Lactobacillus or Lactococcus, and exhibit, when theabsorbent diaper is worn regularly for a short or longer period,antagonistic properties against undesirable strains of microorganismsfrom the families Enterobacteriaceae, Micrococcaseae, Psuedomonadaceaeand Ascomycetes and the genus Streptococcus, and present or arising inthe absorbent diaper or in the urogenital zone of the wearer; andwherein the added microorganisms are added in such quantities and havesuch activity as to restrain the growth of undesirable species ofmicroorganisms to such an extent as to prevent the generation ofundesirable odors in the absorbent diaper.
 8. The absorbent diaperaccording to claim 7, wherein the microorganisms exhibiting antagonisticproperties are placed in the outer sheet of the absorbent article. 9.The absorbent diaper according to claim 7, wherein the microorganismsexhibiting antagonistic properties are placed in the absorbent structureof the absorbent article.
 10. The absorbent diaper according to claim 7,wherein the microorganisms exhibiting antagonistic properties are placedin a loose insert product in the absorbent article.
 11. The absorbentdiaper according to claim 7, wherein the microorganisms exhibitingantagonistic properties are placed between two layers in the absorbentarticle.
 12. In an absorbent diaper including added microorganisms, theimprovement wherein the added microorganisms are selected from the groupconsisting of Lactobacillus acidophilus, Lactobacillus curvatus,Lactobacillus plantarum, and Lactococcus lactis, and exhibit, when theabsorbent diaper is worn regularly by a wearer, antagonistic propertiesagainst undesirable strains of microorganisms selected from the groupconsisting of Proteus mirabilis, Proteus vulgaris, Escherichia coli,Candida albicans, and the genera Klebsiella, Enterococcus,Staphylococcus, Streptococcus and Pseudomonas, said strains ofmicroorganisms being present or arising in the absorbent diaper or inthe urogenital zone of the wearer of said absorbent diaper; and whereinthe number of added microorganisms per absorbent diaper exceeds 10⁶ cfuso as to restrain the growth of undesirable species of microorganisms tosuch an extent as to prevent the generation of undesirable odors in theabsorbent diaper.